The G-25.2 monoclonal antibody specifically recognizes CD11a which is also known as Leukocyte function-associated molecule 1 alpha chain (LFA-1A or LFA-1α). CD11a is a ~180 kDa type I transmembrane glycoprotein that is encoded by ITGAL (Integrin subunit alpha L) that belongs to integrin α-chain family. CD11a is a leucocyte adhesion receptor that noncovalently complexes with CD18 to form the LFA-1 heterodimer (CD11a/CD18) which binds to intercellular adhesion molecules (ICAMs) expressed on target tissues including ICAM-1 (CD54), ICAM-2 (CD102), ICAM-3 (CD50), ICAM-4, or ICAM-5. The CD11a antigen is expressed on virtually all normal peripheral blood leucocytes. It is essential for many immune responses that require cell-to-cell contact, such as lymphocyte adhesion, natural killer (NK) and T-lymphocyte cytolysis, and T lymphocyte proliferation. Activation of lymphocytes through the T-cell antigen receptor (TCR) upregulates LFA-1 function, converting the antigen to a high-avidity state. Expression of LFA-1 on monocytes is upregulated by γ-interferon (IFN-γ). While normal cells possess both the α and β LFA-1 chains, cells of subjects with some leukemias, lymphomas, or leucocyte adhesion deficiency (LAD) may lack the entire LFA-1 molecule or the α or β chain. The absence of LFA-1 on tumor cells may provide a mechanism for their escape from immune surveillance.
The antibody was conjugated to BD Horizon™ BUV496 which is part of the BD Horizon Brilliant™ Ultraviolet family of dyes. This dye is a tandem fluorochrome of BD Horizon BUV395 with an Ex Max of 348-nm and an acceptor dye with an Em Max at 496-nm. BD Horizon BUV496 can be excited by the ultraviolet laser (355 nm) and detected with a 515/30 nm filter with a 450LP. Due to the excitation of the acceptor dye by other laser lines, there may be significant spillover into the channel detecting BD Horizon V500 or BV510 (eg, 525/40-nm filter). However, the spillover can be corrected through compensation as with any other dye combination.